Pendergrafts & King Ranch family legend

My late grandmother always relayed a story told to her by her father-in-law, Dr. George Irving Pendergraft, son of Thomas Pendergraft, son of Moses Pendergraft, son of Job Pendergrass.The story is that some Pendergrafts were surveyors in early Texas and rec'd land grant for services.This would have been mid- to late-1830's.One brother was murdered for deed to land, which became core of King Ranch.This does not correspond with any family research I can find.However, my grandfather had this original deed, along w/surveys in 1950's.Could this have happened in a maternal line?Has similar story been passed along in other branches?Would make a great novel.